The present-day technology of generator construction is characterized by trends toward building-up the unit power of generators, with the result that in the present state of the art, the generator stator windings must be designed to handle high rated currents (from 10 to 60 kA). Hence, at the existing levels of generator voltages (from 15 to 27 kV), the dimensions of stator winding bars must be increased substantially, and the length of stator winding coil end bars must be extended accordingly. Furthermore, manufacture of modern high-power generators is practical due to the realization of direct liquid cooling of the generator winding, with the dimensions of the generator stator winding bars increased still further to furnish passages for supply of coolant. In its turn, the length of the stator winding coil end bars has extended even more, with direct cooling of the stator winding bars provided by means of intricate devices for supply of coolant which in most cases do not permit raising the generator voltage substantially above the established level /cf. V. V. Titov, G. M. Khutoretzkiy, G. A. Zagorodnaya, G. P. Vartanian, D. I. Zaslavskiy and A. I. Smotrov, " Turbo-Generators. Design and Construction", Energia Publishers, 1967, Leningrad, pp. 38 through 45 and 70 through 72 (in Russian)/.
Known in the art is a device for attachment of generator winding coil end bars, wherein the coil ends are held by shrink rings embracing the bars on the outside by a set of spacers disposed in gaps between individual bars. Each bar in a bottom and a top layer is fastened to each shrink ring. The shrink rings are attached to the generator stator by means of brackets. The spacers are fastened to the bars, and the coolant is supplied to the stator winding bars through rubber hoses (cf. V. V. Titov, G. M. Khutoretzkiy, G. A. Zagorodnaya, G. P. Vartanian, D. I. Zaslavskiy and A. I. Smotrov, "Turbo-Generators. Design and Construction", Energia Publishers, 1967, Leningrad, pp. 188 through 192).
In the prior-art device, the winding coil end bars are attached to the generator stator on one side only, and this is obviously insufficient for longer bars of the winding coil ends used in higher unit power generators designed for output voltages above the existing level, so that the generator dependability is impaired.
The above method of attachment of the shrink rings and spacers in the prior-art generator is not quite reliable.
The closest analog to our invention is a device for attachment of coil ends in a generator stator high-voltage winding (cf. USSR Inventor's Certificate No. 215305 H02K 3/50, published in the Bulletin of Discoveries, Inventions, Designs and Trade Marks, No. 13, Nov. 3, 1963). The foregoing device incorporates a shrink ring mounting supporting brackets attached thereto, insulation spacers furnished with spacer wedges disposed therebetween and positioned on external surfaces of the coil end bars, and extra spacers furnished with the spacer wedges disposed therebetween and positioned between the coil end bars. The insulation spacers are clamped at the ends thereof by insulation rings. A hollow shrink ring through which coolant is supplied serves as a coolant header.
The prior-art method of attachment of the generator stator high-voltage winding coil ends permits securing the coil end bars only on one side facing the generator end plate, and is therefore insufficiently reliable, the coil end bars in modern high-power generators being quite long (about 1/5 of the active length thereof per each side).
Owing to the use of supporting brackets and shrink rings for attachment of the stator high-voltage winding coil ends, a long range of insulation and constructional materials are required.